Current knowledge on practices targeting soil fertility and agricultural land rehabilitation in the Sahel. A review

Abstract

AbstractImplementing sustainable production practices to rehabilitate soils is a grand challenge of our day, particularly for resource-poor farmers. The West African Sahel requires attention to balancing the need for increasing agricultural production against harsh environmental conditions. While there is much research documenting technologies for soil regeneration in the Sahel, there has been limited focus on how agricultural practices contribute or exacerbate these efforts. Previous assessments of agricultural practices in this region have been largely descriptive, and some soil ameliorating practices have been promoted with little empirical evidence on their effectiveness. Here we systematically review the literature on soil fertility and conservation practices that have been studied within West African Sahelian agricultural systems. We identified practices in the West African Sahel that have been tested to improve soil fertility and reduce land degradation, and summarized the outcomes of these practices. A unique contribution of this review is the assessment of site-specific conditions and contexts under which practices are most effective in studies which recorded these specific characteristics. We found that research in this area is dominated by chemical fertilizer and organic amendment practices, with moderate to few studies focused on soil and water conservation, crop diversification, or agroforestry. Additionally, most studies consisted of single practices rather than combining practices that target the range of biophysical limitations farmers face in agricultural production. These limitations highlight the need for increased research testing combinations of practices across long-term on-farm studies to generate stronger evidence of conditions under which practices best perform. These findings provide key lessons for research and extension on sustainable agricultural management under the challenging conditions of the Sahel.